"For years, and unbeknownst to eBay, Amazon has been engaged in a systematic, coordinated effort to infiltrate and exploit eBay's proprietary M2M system on eBay's platform to lure top eBay sellers to Amazon," eBay alleges.

eBay says the scheme came from the top, claiming Amazon sent identical messages to eBay sellers from Amazon addresses.

No Robin Hood

The poaching allegedly began in 2015, but eBay reportedly didn't find out until last month. The company sent a warning shot before filing suit.